The Argentine stem weevil (ASW), Listronotus bonariensis (Coleoptera: Curculionidae), is an exotic pasture pest in New Zealand. It was first detected in the 1920s, and by the 1980s was causing hundreds of millions of dollars' damage to pasture per year. In the early 1990s, a parasitoid wasp from the host range of ASW, Microctonus hyperodae (Hymenoptera: Braconidae), was introduced as a biocontrol agent. Attack rates were initially around 80%, providing effective control, but have subsequently declined to around 20%, suggesting the evolution of resistance in the host. Along with the agricultural importance of this problem, measuring the genetic variation in both the sexual host and the asexual parasitoid is an exciting opportunity to investigate the evolution of resistance in a biocontrol system. We are working on de novo, shotgun genome and transcriptome sequences for both species and population surveys using genotyping-by-sequencing (GBS) and targeted resequencing of the 16S ribosomal RNA gene. These results are guiding our efforts to determine the mechanism of resistance using functional experiments including RNAi, genome editing and RNAseq.